Just keep the Pursuit Bot open and buy slots manually when level 60.
I have a few solution for all of you that cannot buy carslot for free.
Before you start make sure you have set the resolution to 800x600 ,LCSC BotV2 and LV60
First Solution
Make sure you already lv60 in the system record. I found that when i reach lv60 and i check my driver profile through nfstime i found that my lv still below 60.
Second Solution
Before you buy the car slot make sure you have also set you game language to English from the Game Launcher and computer system locate to English united state.
Go to Control Panel, click on Region and Language, Choose the Administrative Tab and change the Language for non-Unicode program to English (United State)
This is how i unlock my car slot after i read through all the post in the forum.
Lastly, Sorry for my bad english.